The connection pin for a silent chain may be of a round pin type having a circular section, or a locking joint pin type. The present invention is concerned with a silent chain having a connection pin of the locking joint pin type. The locking joint pin, as shown by the prior art silent chain of FIGS. 1-5, is composed of a pair of long and short connection pins P.sub.1 and P.sub.2 which are in contact with each other on the rolling surfaces thereof as shown in FIG. 1. At the end of the long connection pin P.sub.1, a guide link G shown in FIG. 3 is fixed by mounting and fixing holes H and H at the end of the long connection pin, and a number of meshing link plates M having a pair of meshing teeth T are pivotally connected on the short connection pin P.sub.2.
Accordingly, when tension acts on the silent chain, the link plates are stretched alternately and reversely so that a shearing force acts on the connection pin whereby trouble can occur where the guide link G connects to the long connection pin P.sub.1 and defines the smallest sectional area which can rupture. In view of this, as disclosed in Japanese Patent Laid-Open No. 101940/1987, to prevent occurrence of the aforesaid rupture, an auxiliary plate having the same shape as that of the meshing link plate is placed on the guide link to increase the shearing strength.
The prior art disclosed in the aforementioned Patent Laid-Open No. 101940/1987 has a disadvantage in that by the lamination of the auxiliary plate, the width of the chain increases and the weight of the chain increases so as to constitute an obstacle to high speed operation of the chain.
According to the present invention, the shearing strength of the connection of the guide link to the long connection pin is not increased, but the rigidity of the guide link is made to be 1/2 of the rigidity of the meshing link plate, whereby the shearing stress on the long connection pin by the guide link is reduced by half to equally share the tensile pull of the guide link and the meshing link, thus preventing the long connection pin from being ruptured.